Ph.D. Theses

A component property named lookback, defined as the ability to change the
past locally, will be discussed. Lookback enables a new class of PDES
synchronization protocols, which unifies two previously known PDES
techniques:
out-of-timestamp order execution and local rollback. Lookback has proven to
be
more commonly present that lookahead, the basis for traditional conservative
PDES synchronization protocols. Moreover, lookback-based protocols are shown
to be capable of completing the simulation earlier than the limit imposed by
the critical times of events, which is an insurmountable bound for
traditional
conservative protocols and optimistic protocols without optimization.
Furthermore, there exist four types of lookback, referred to as direct
strong
lookback, universal strong lookback, direct weak lookback, and universal
weak lookback. While strong lookback is required for lookback-based
protocols,
it has been demonstrated that all types of lookback can be exploited to
improve the performance of optimistic protocols by reducing the number of
rollbacks and anti-messages.